I can't see my objects in Solid mode, but I can see them in Rendered Mode
When I open your file its not visible even in Render Mode.
Really strange behaviour.

But if you are looking for solution - turn off and on your "OBJECT" collection (check mark on left side of Outliner editor).



Note: Do the same for "MAIN" collection, there are also hidden objects that should not be (like ceiling and totaly discoverable window object). Is not the blend file from some older blender version?